This lesson offers step by step instructions for converting U.S. ounces into gallons. You'll also learn how to convert from the Imperial (U.K.) ounce to gallon measurements as well.

Ounces to Gallons

The most important thing to remember about changing ounces to gallons is that there are 128 ounces in every gallon.

Another way to think of it is 'for every 128 ounces you have 1 gallon'. This leads directly into the formula: xounces/128 = y gallons (notice this formula divides the number of ounces into groups of 128 to determine the number of gallons).

Let's try an example: A farmer measures his cows' milk production by the ounce but sells it by the gallon. If the farmer collected 19,200 ounces of milk in a week, how many gallons of milk will he be able to sell?

Step 1:

Remember the formula.

x ounces/128 = y gallons

Step 2:

Substitute known values into the formula. Here the number of ounces is 19200.

19200/128 = y gallons

Step 3:

Calculate the answer.

150 = y gallons

The equivalent number of gallons is 150. It is most appropriate to answer word problems with full sentences, so the answer to this problem is best written as 'The farmer will be able to sell 150 gallons of milk this week'. Remember that ounces can be abbreviated as oz and gallons can be abbreviated as gal in your answers.

Tips and Another Example

Tips

The key conversion rate of 128 ounces = 1 gallon is only for ounces and gallons in U.S. measurement. The conversion rate for ounces and gallons in the U.K. is 160 (Imperial) oz = 1 (Imperial) gal. You wold work the problem using the same steps, just use 160 instead of 128 in the calculation.

Another Example

Convert 28 gallons into ounces (U.S. measure).

This problem works the same as the first.

Step 1:

Our formula is xounces/128 = y gallons

Step 2:

Substitute the values, giving x ounces/128 = 28

Step 3:

Calculating, we get 28 x 128= 3,584 (multiply both sides by 128 to isolate the ounces variable), which is our answer

Finally, format the answer, giving us 3,584 oz.

There is no need to format the answer in sentence form because the original question was not a word problem.

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